C++ Program to Count Set Bits (1s) in Binary with Explanation
C++
Hard
Operators
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1 min read
166 words
This problem helps you practice core C++ fundamentals in a practical way. It builds intuition around binary, count, representation. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Count how many 1s are in binary representation of number.
Real Life: Used in computer architecture, compression.
Input Format
An integer N.
Output Format
Count of 1s in the binary representation of N.
Constraints
• N ≥ 0
• Use bitwise operations
Concept Explanation
The number of 1 bits in binary shows how many bits are set.
This is used in computer architecture and data compression.
Step-by-Step Logic
1.Take input number N.
2.Initialize count = 0.
3. While N > 0:
• Check last bit using N & 1.
• If it is 1, increment count.
• Right shift N by 1.
4.When N becomes 0, stop.
5.Print count
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
void operator_q11_count_set_bits() {
int num = 29; // Binary: 11101
int count = 0;
int temp = num;
while(temp > 0) {
if(temp & 1) { // Check last bit
count++;
}
temp = temp >> 1; // Right shift
}
cout << "Number: " << num << endl;
cout << "Set bits (1s) in binary: " << count << endl;
}
Output Example
Output:
3
Explanation: 13 → binary 1101 → three 1s)
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Count how many 1s are in binary representation of number.
Real Life: Used in computer architecture, compression.
Input / Output
Output
Count of 1s in the binary representation of N.
Constraints
• N ≥ 0
• Use bitwise operations
Examples
Output:
3
Explanation: 13 → binary 1101 → three 1s)
Explanation
Concept Explanation
The number of 1 bits in binary shows how many bits are set.
This is used in computer architecture and data compression.
Step-by-Step Explanation
1.Take input number N.
2.Initialize count = 0.
3. While N > 0:
• Check last bit using N & 1.
• If it is 1, increment count.
• Right shift N by 1.
4.When N becomes 0, stop.
5.Print count
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
void operator_q11_count_set_bits() {
int num = 29; // Binary: 11101
int count = 0;
int temp = num;
while(temp > 0) {
if(temp & 1) { // Check last bit
count++;
}
temp = temp >> 1; // Right shift
}
cout << "Number: " << num << endl;
cout << "Set bits (1s) in binary: " << count << endl;
}
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